Apparatus for burning liquid fuel



4 Sheets-Sheet l N QQ R Feb. 9, 1943. R. w. BECKETT APPARATUS FORBURNING LIQUID FUEL Filed Feb. 4, 1958 lN\ IENTOR ATTORNEYS u h a B w ma m M Feb. 9, 1943. w E -f 2,310,274

APPARATUS FOR BURNING LIQUID FUEL FiledFeb. 4, 1938 4 Sheets-Sheet 2INVENTOR i e iw WBecket;

\ ATTORNEYS Feb. 9, 1943. w, BECKETT 2,319,274

APPARATU S FOR BURNING LIQUID FUEL Filed Feb. 4, 1938 4 Sheets-Sheet 3INVENTOR Rey inald WBeckett BY MHZ ATTORNEYS Patented Feb. 9, 1943UNITED STATES PATENT OFFICE Reginald -w. Becket Elyria, om ApplicationFebruary 4, 1938, .Serial No. 188,731

.19 Claims.

' This invention relates to oil burners and more particularly to burnersof the gun type in which a blast or current of combustion air is forcedpast and around a nozzle ejecting fuel under high pressure and into afurnace or other combustion chamber.

It is an object of the invention to provide an improved oil burner inwhich a spiral motion is imparted to the combustion air and the air isgiven an increased turbulence or agitation in the.

region of the fuel ejecting nozzle so that an improved mixing of thefuel and air-is produced and an atomized mist of highly combustible fuelis projected from the mouth of the burner.

Another object is to provide an oil burner having all moving or drivenparts in a unit which is readily removed from, or replaced in, theburner. Another object is to provide an air control for a burner of thetype having an air inlet and'an air discharge, such control beingarranged to regulate the quantity of air moving through the burner bothwhen the burner is active andwhen the burner is idle.

Another object is to provide a burner in which 1 the several parts arereadily accessible for adjustment or repair and in which individualparts may be replaced with a, minimum of effort.

Another object is to provide a burner simple in design and constructionand relatively inexpensive to manufacture, and one which may be quicklyand easily installed with maximum precision and without the use ofspecial appliances, tools or other equipment.

Suitable embodiments of the invention are illustrated in theaccompanying drawings, in which:

- Figure l is a side elevational view partly in section and with partsremoved showing a burner in position for operation in a conventionalfurnace and taken substantially on the line l-l of Fig. 3;

Fig. 2 is a fragmentary enlarged detail plan view showing the controlfor the air inlet door. This view is taken substantiallyfrom the lineindicatedat2-4 ofFlg.1; 1

Fig. 3 is a rear elevational view of the burner with parts broken away;

Fig. 4 is a front elevational view of the burner;

Fig. 5 is a fragmentary sectional view taken substantially on the line5- -5 of Fig. 1;

Fig. 6 is an enlarged fragmentary detail in section showing the mountingfor the air inlet control door;

Fig. 'l is a view with parts the moving parts of the burner which areremov able therefrom as a unit;

Fig. 8 is a transverse vertical sectional view with parts removed takensubstantially on the line 8 8 of Fig. 1; Fig. 9 is a detail of areplacement or substitute supporting cushion block for changing theheight of the burner;

Fig. 10 is a fragmentary detail view in section taken substantially onthe line Ill-l0 of Fig. 1;

Fig. 11 is a fragmentary detail view in section taken substantially onthe line ll-ll of Fig. 3, showing the hinge mounting for thetransformer;

Fig. section showing the construction of the electrode contactterminals; i;

Fig. 13 is a fragmentary elevational detail showing a modification inwhich a spring is emposition;

Fig. 14 is a fragmentary sectional view taken substantially on the linell-Il of Fig. 13

Fig. 15 is a side elevational view in section and with parts removedshowing a modification of the burner installed in a furnace having arecess or pocket; and

Fig. 1c is a detail view partly in section aid taken substantially onthe line lB-IB of Fig. 15. Referring to Figs. 1 through 12 of thedrawings by numerals, of reference, which indicate like parts throughoutthe several views, the burner comprises a pedestal or base, indicatedgenerally by the numeral I, which is surmounted by and supports a mainbody portion or housing, indicatedgenerally by the numeral 2. Ahorizontally disposed air or blast tube 3 is secured to the lowerportion of the housing 2 at one end thereof by cap screws or studs Iwhich extend through a-radially directed flange ll formed at the inletend of the air tube. On the upper portion of the housing 2 at. theend'thereof opposite the blast tube 3 -a The blower 9 is received in achamber it formed in the upper portion of the housing 2 and forcesbroken away showing air downwardly through a throat l5 tangentially 12isan. enlarged fragmentary-detail in ployed to retain the inlet controldoor in open into inlet end iii of combustion air passageway [1extending longitudinally through the bottom of the housing 2 and the airtube 3.

The fuel pump and pressure regulating device 8, 'which is preferablymounted on the motor and bell in the manner set forth in my co-pendingapplication, Serial No. 190,309, filed February 12, 1938, draw liquidfuel through supply conduit l8 and force it under relatively highpressure through fuel pressure conduit l9 having a flexible loop 20 intofuel pipe 2| supported by bracket 22 and spider 23 in the air tube 3. Avaporizing or spray nozzle 25 is secured on the end of the fuel pipe 2|at the discharge end of the air tube 3 so that its outlet orifice 26 isdisposed substantially in the plane of the smallest cross-sectional areaportion of a burner head 21, to be later described. Air forced throughthe passageway [1 by the blower 9 and moving in a helical pathcommingles with the oil spray emerging from the nozzle orifice 26 toform a mist of finely dispersed oil particles which burn in combustionchamber 28 of a heating unit such as a domestic furnace.

The housing 2 is symmetric in external appearance and of generally ovateform as viewed from either end. It is carried in an upright position onthe base I, being of a materially greater height than width and of amaterially greater width than length. The housing is of substantiallyuniform length from top to bottom and has a top wall 30 0f generallyrounded form merging into a relatively straight vertical side walls 3|and 32. Inwardly curving or rounded bottom walls 33 and 34 extenddownwardly as continuations of the side walls 3! and 32 and terminate ina downwardly directed socket 35, to be later described. Rear end wall 36carries the bracket 5 which supports the removable motor unit, and frontend wall 31 carries the air tube 3 as mentioned above.

The blower chamber l4 (Fig. 8) is of the form commonly employed withrotary blowers of the sirocco type having axially extending blades, andi partially defined by a curved internal wall or partition 38 whichextends between the end walls 36 and 31 of the housing 2 from a point 39where it is formed into the top wall 33 of the housing at substantiallythe center thereof downwardly to the left in a circular fashion and thento the right, as viewed in Fig. 8. The lower end of the wall 38 extendsbeyond the middle of the housing and to the cut off of the throat IS.The radial space between the peripheral margin of the rotary blower 9and the walls of the chamber l4 progressively increase from the cut offof the throat l5 in a clockwise direction around the rotational axis ofthe blower substantially to the throat I 5. This increase in the freeradial crosssectional area of the housing available for the flow of airis in the direction of rotation of the blower rotor 9, indicated by thearrow of Fig. 8.

In the bottom of the housing 2 is formed the inlet end I 6 of thepassage l1, as previously mentioned. Air moving through the throat IS ina downward direction is directed tangentially into the passage portionl6 by the curved bottom wall 34 of the housing, the inside surface ofwhich gradually approaches the passage l6 and is tangent thereto atsubstantially the bottom of the housing.

One side of the inlet end iii of the passage, opposite the throat I5, isdefined by an internal wall or partition 42 which starts substantiallyat the bottom center of the housing 2 where it is connected to the lowerpart of the bottom wall 33, as indicated at 43, and is then curvedupwardly to the left and then to the right in a clockwise directionfollowing the general curvature of the passage I1 as defined by the tube3. The upper end of the partition 42 and the lower end of the partition38 are joined by a short. vertically disposed partition 44 whichpartially defines the throat IS. The partition 42 i curved or slopedlongitudinally of the inlet portion l6 of the air passage as shown inFigs. 1 and 10. This curve.- ture is progressively increased from thelower portion 43 to the top portion where the partition 42 joins thevertical partition 44. The margin 45 of the partition 42, adjacent theend wall 36 of the housing 2, progressively approaches the axis of theair passage l1, while the margin 46 of the partition 42, adjacent theend wall 31 of the housing, remains substantially flush with theinternal wall of the air tube 3. Air entering the inlet l5 of the airpassage I1 tangentially through the throat i5 is directed in a helicalpath to flow through the tube 3. The opening in the front end wall 31 ofthe housing 2, which is covered by the air tube 3, is of substantiallythe same effective cross-sectional shape and area as the correspondingend of the air passage in the tube 3 so that the walls of the inletportion it; are substantially flush with the walls of the air tube 3. Noportion of the inlet end I6 of the air passage l1, which is formed inthe housing 2, is of greater efi'ective cross-sectional area than theportion of the passage 11 which is formed in the tube 3. Preferably,there is a progressive decrease in the effective cross-sectional areainlet portion I6.fromthe plane of abutment between the fiange H of thetube 3 and the wall 31 to the rear end wall 36 as appears in Figs. 1 and10.

Tube 3 is substantially circular in cross-section throughout its lengthand has a portion 41 of cylindrical form and uniform diameter adjacentthe housing 2 which merges into a tapering portion 48 which extendstoward the discharge end of the tube where a second cylindrical portion49 of uniform internal diameter and relatively short axial length isformed. The walls of the tube 3 are relatively thick and of heavysection at the discharge end thereof, preferably being in the form of anintegral, thick-sectioned, annular collar 50 which reinforces the tubeend and receives the screws which hold the head 21. A circular, radiallydirected flange 53 is integrally formed about the large diameter end ofthe head 21 and circumferentially abuts against the annular collar orthickened section 50 on the discharge end of the tube 3. A pair ofscrews 63 extend through suitable drill holes in the flange 53 and arethreadedly secured in the collar 50 to clamp the head 21 in heatexchanging circumferential contact with the collar. The relativelyextensive radial area of contact between the head 21 and tube 3facilitates the conduction of heat from one of these metal parts to theother. Accordingly, heat is rapidly conducted away from the head 21during operation of the burner so that it is maintained at a relativelylower temperature than would otherwise prevail, thus reducing thedeterioration of the head and increasing its life.

Another pair of screws 5| extend through an annular holding ring 52,disposed about the head 21, through the flange 53 and are threadedlyreceived in the annular thickened collar portion 50 at the discharge endof the tube 3. The ring 52 and flange 53 preferably have substantiallythe same outside diameter and the ring is axially movable over anexternal cylindrical portion 54 of the head 21 which extends forwardlyfrom the base of the flange 53. Between the ring 52 and flange 53, andseating on the cylindrical portion 54 of the head, is an an-- nular ring55 of fireproofflbrous material such as asbestos. This ring is clampedbetween the holding ring 52 and flange 53 by the screws which also holdthe head 21'to the tube 3.

In the event that a new ring of asbestos 55 is to be fitted in place onthe head 21, only the screws 5| need be removed, the screws 53rethreaded stud 55 which extends through an elongated slot 55 formed inthe bottom of the cylindrical portion 41 of the air tube '3. Preferably,the stud 55 is made separately from the bracket 22 and threadedlysecured therein. Ac cordingly, the bracket 22 may be adjustedlongitudinally in the tube' 3 so as to vary the position of the nozzle25 with respect to the head 21. A

nut 51,0n the stud 55 looks the bracket in adjusted position and thenovel shape of the tube 3 which provides a. cylindrical portion forholding the bracket 22 retains the fuel pipe 2| cenmaining in positionto retain the head on the tube 3. The heat resisting asbestos ring,covered by the metal ring 52, protects the head from the heat in thecombustion chamber and minimizes the corrosion of the screws 5| and 53so 'that the screws may be more easily removed fuel oil. This shoulder55 is adjacent the small diameter cylindrical portion 49 of thepassageway in which is located the spider 23. From the shoulder 55 thehead 21 is tapered and the internal walls thereof converge to provide aprogressively decreasing, substantially circular cross-sectional area inthe direction of air flow. At substantially the region of smallestcrosssectional area the head 21 is formed with a shoulder 51 whichfurther turbulates or agitates the moving air. From the shoulder 51 tothe extreme end of the head 21 there is anoutwardly tapering outlet ormouth 58.

A downwardly sloping passage or drill hole 59 extends through the bottomwall of the head 21 from the inside thereof between the annularshoulders 55 and 51, through a depending boss 55 integral with the head,to the foremost edge of the head. This hole servesas a drain for fueloil that may drip from the nozzle 25 and directs the same into thecombustion cha'mber28. Preferably the end of the hole 59 inside the headis enlarged or dished to more effectively drain off the oil.

When installing the burner in a heating system, such as a domesticfurnace, having. the refractory lined combustion chamber or fire pct 25the asbestos ring 55 is moistened to render it pliant and flexible sothat the head 21 can be inserted into opening 5| in the fire pot 25 andthe asbestos ring 55 accommodates itself to the walls of the opening 5|to effect a circumferential seal therewith. If desired, an additionalquantity 52 of plastic asbestos cement or thelike may be packed aroundthe head 21 in advance of the asbestos ring 55 so as to provide a morepermanent seal and to protect the head 21 from the heat of the fire pot.

The bracket 22 which holds the fuel pipe 2| has a curved or cylindricalbottom surface 54 which corresponds in curvature to the internalcylindrical surface of theportion 41 of the tube 3. This curved surface.54 assists inaligning the bracket in the air passageway i1 and affordsa snug fit between the bracket and tube. The bracket is held in placebya depending tered in the air passageway H in all positions ofadjustment. The cylindrical portion 49 at the discharge end of the airtube which has a uniform internal diameter permits the spider 23 to movelongitudinally in the passageway |1 while the ends of the spider legsmaintain sliding engagement with the walls of the tube. Thus both endsof the fuel oil pipe 2| are supported and retained centrally in the airpassageway |1 regardless of the movement of the bracket 22 and spider 23in adjusting the nozzle 25.

A pair ofignition electrodes 58 and 59 are disposed longitudinallythrough the passageway i1- slightly above and on opposite sides of theoil pipe 2|. These electrodes are mounted in porcelain insulators 15held in a clamp 1| on the top of the bracket 22. The forward ends of theelectrodes and 59 are directed toward one another in the region of theorifice 25 of the nozzle 25 so that a spark across the electrodesignites the atomized fuel.

A transformer, carried in a box or second housing 13 disposed'againstthe rear end wall 35 of the housing, furnishes high tension current tothe electrodes 55 and 59. Conductors 14 and 15 enclosed by insulators 15extend into the inlet end lie! the air passageway H from the transformerbox 13 through an opening, 11 formed in the rear wall 35 of the housingwhich is normally covered by the transformer box 13. Each of theconductors is provided with a springq like brush 18 formed of suitablesheet metal such as bronze or brass and which extends upwardly j and atright angles across the axes of the electrodes 55 and 59.

Electrical contact is'made between the brushes 15 and the electrodes bymeans of contact sleeves 19 (Fig. 12) slidably received on the threadedends of the electrodes and urged toward the brushes 15by helicalcompression springs 85. Each of the springs 85 has one end adjustablyretained on the electrode by a reduced diameter portion 5| which gripsthe electrode, and a nut 82 which is threaded onto the electrode. Theend of each of the springs 85, opposite the reduced diameter portion 8|,bears against a shoulder formed by increased diameter head portion 83 ofthe sleeve 15. Thus the spring 85 is partially carried over 'the sleeve19 to have sliding engagement therewith and prevent the individual turnsof the spring from being caught on the threaded electrodes. The springs85 are adjusted so that the heads 53 naturally take the positionindicated by the broken lines in Fig. 12, and are moved to substantiallythe full lin position when enzaged by the brushes 18. In thus effectingelectrical contact for the flow of current throughthe electrodes 55 and59 the brushes 15 are likewise deflected from the broken line positionto the full line position of Fig. 12 and placed under stress.

rear end wall 36 of the housing 2. Flange portions 86 and 81 of the plat85 extend beyond the sides of the box 13 and are utilized in attachingthe box to the housing. The flange 86-has a vertically disposed pianotype hinge 88 secured thereto by suitable means such as spot welding.The upper portion of this hinge is seated in a recessed portion of thehousing wall 36 (Fig. 11) and is secured thereto by flat head machinescrew 89. The lower portion of the hinge is similarly secured to an ear90 (Fig. 4) extending from the housing 2.

The flange 9'! of the plate 85 is secured to the housing 2 and an ear 9Iby fillister head screws 92 (Fig. 1). This novel mounting of thetransformer facilitates opening of the inlet end of the combustion airpassageway If so that adjustment or removal of the nozzle and electrodesmay be made through the rear wall of the bumer. The unique contactarrangement of the high tension electrical conductors for the electrodes68 and 69 eliminates the use of loose high tension wires thus renderingthe burner safer and less likely to get out of order. Each time thetransformer box I3 is pivoted on the hinge 88 to uncover the opening Hthe secondary or high voltage connections to the electrodes 68 and 69are automatically opened. When the transmission box 13 is pivoted to theclosed position to cover the opening 11 the ignition connections to thetips of electrodes 68 and 69 are automatically closed. This featur isadvantageous in that manual disconnection of the high tension electrodesfrom the transformer is unnecessary in removing the electrode assemblyfrom the burner for service purposes. Similarly, manual connection ofthe high tension leads is obviated or eliminated when th burner isreassembled.

A wide range of longitudinal movement of the electrodes 68 and '69 inthe passage I! is permitted by the contact brushes 18 and the springpressed contact sleeves I9 which are arranged to maintain a. firm andpositive electrical connection throughout such movement.

All the high tension conductors of the burner ignition system arecontained or enclosed within metal parts so as to be concealed orshielded. Thus the possibility of damage or injury to the high tensionleads and conductors is minimized as well as avoiding the possibility ofa person receiving an electrical shock from accidental contact with amember of the high tension ignition circuit. Each leg of the hightension circuit is of substantially the same length and resistance, andsubstantially the same distance from the walls of the tube 3 whichserves as a shield. In this manner, the possibility of radiointerference and the like being caused by the burner ignition system isreduced to a minimum, the middle of the secondary winding of thetransformer in the box 13 being grounded in the usual manner.

The end opening 11 nto the longitudinally extending air or blast tubepassageway II eliminates the necessity for a removable inspection plateor door in the side of the blast tube 3 for adjustin and otherwiseservicing the burner. This feature is particularly advantageous ininstallations where it is diflicult to get at the air tube because ofclose quarters. The adjustment of the nozzle 25 and electrodes 68 and 69can be effected through the opening I1 without withdrawing the head 21of the burner from the opening in the fire box. If desired, the assemblyof electrodes, nozzle and fuel conduit can be adjusted while the burneris in operation by loosening nut 61 on stud 65 of bracket 22.

Air is drawn into the burner by the blower 9 through a downwardlydirected inlet opening in a hood 94 formed on the front wall 31 of thehousing 2. An air chamber 95 in the hood 94 communicates with the blowerchamber I4 through a circular opening 96 formed in the front wall 31 andconcentric with the shaft I2 of the blower and motor.

An air gate 91 is mounted oif center on reduced diameter pin ends 98(Fig. 6) of pivot screws 99 which are threadedly carried in alignedholes through the side walls of the hood 94. The screws 99 preferablyhave enlarged knurled heads I00 on the outside of the hood 94 so thatthey may be adjustably screwed toward or away from one another andshoulders IOI thereof may be made to frictionally engage apertured pivotbrackets I02 which are secured to the air gate 91 to support the sameand are received on the pin ends 98 of the pivot screws. Thus. bytightening the screws 99 against the brackets I02 the gate 91 may beretained in either opened or closed or in intermediate adjustedposition, as desired, to regulate the flow of air through the burner.Upon loosening the screws 99, the gate 91 is freely pivoted on the pins98 and falls by gravity to close the inlet opening into the hood exceptwhen held in open position by air pressure.

An adjusting rod I04 is vertically disposed in the air chamber 95 androtatably journaled in a drilled hole in the top of the hood 94. Anenlarged knurled head I05 is secured on the top of the rod I04 above thehood 94 so that the rod can be manually rotated. An indexing pin I06extends through the rod I04 and extends radially therefrom. This pinrides in a recess I0! formed in the top of the hood 94 and havingapproximately a 90 opening therein so that the rotational movement ofthe rod I04 is limited to about 90. The rod I04 is urged downwardly by ahelical compression spring I09 which seats on a washer I09 secured onthe rod I 04 and a washer IIO bearing upwardly against the inside of thetop wall of the hood 94. A foot III is formed at i the bottom of the rodI04 by bending the latter substantially through 90; This foot isdisposed a short distance above the air gate 91 when the latter isclosed and it is preferably provided with a rubber covering IIZ tosilence the contact between the foot and the gate when the movement ofthe latter is arrested by the foot. When the pivot screws 99 areloosened so that the air gate 91 is free to pivot on the pins 98, thegate is opened .by the air pressure on the underside thereof when the:blower 9 is rotating. The amount that the air gate will open under theinfluence of air pressure can be varied or adjusted by rotation of therod I 04 which moves the foot III to various positions. For example,when the rod is rotated to its extreme counterclockwise position asviewed in Fig. 2 and as limited by the pin I06 in the recess I01, thegate 91 will be able to open only a minimum amount whereas movement ofthe rod I04 to its extreme-clockwise position as viewed in Fig. 2 willcarry the foot III to a position substantially parallel with the axis ofthe pivot screws 99 and a maximum opening of the gate 91 is permitted.In this manner by means of the rod I04 the opening of the gate 91 whichregulates the quantity of air forced through the passageway I! by theblower 9 can be adjusted top center of the upr eht portion I I3 of thebrackwhile the burner is in operation to give the most eflicient anddesirable type of flame in the combustion chamber 26. The frictionaleffects of the pin I06 and spring I06'are adequate to tempo-' .rarilyhold the rod I04 while adjustment of the burner is being made. After theadjustment is complete the rod I04 is locked in position by set screw 4.As long as the blower 9 is in operation the gate 91 is held open againstthefoot III of the adjusting rod I04. Upon shutting oiI of which areparallel to the axis of the pivot screws 99 with the inside bottom edgeof. the wall of the ,hood 94 or the end wall 31 of the housing 2. j Themovable parts of the burner; which are removable as a unit shown in Fig.'I, are carried by a substantially U-shaped cradle II5 sebracket 5 bystuds H6 and centered thereon by raised tracks or bosses II1 (Fig. 3).The upstanding arms of the cradle- II5 are provided with metal-bands 6which confine annular rubberrings or'cushions (not shown) embracing thejournal bosses on the bells of the motor 1. Ac-

cured to the floor of the supporting member or An upright portion I I9of the supporting mem- I her 5 is disposed against the upper portion ofthe rear-wall 36 of the housing 2 and a circular opening I is formedthrough the portion H9 9 when removing or replacing the movable parts ormotor drive unit. This opening is closed by the coverplate III which issecured to the portion ing the screws HI and the bolts or studs I I6,dis-' connecting the fuel conduits I8 and I9 and the electric leads tothe motor. Replacement of a new or repaired unit can be quicklyaccomplished and the wall 36 to permit passage of the blower Y et Ipermits the latter to suspend itself from the pin I22 and pivot bygravity .to align the holes 7 forthe studs I. f I

The pedestal or base I has 'a relatively large footing portion I24 whichaffords a wide area support for the burner. Square or rectangular padsor cushions I33 are received in sockets I39 at marginal portions of thefooting portion I24 of the base. Preferably, thepads I33 are three innumber and formed of resilient cushioning or vibration-absorbingmaterial such as. wood, cork, or rubber, thus eifecting a quieting threepoint mounting for the burner. In the event that the surface on whichthe burner is to be supported is irregular or of uneven height, the padsI33 can be made shorter or longer, as required, so as to carry the baseI evenly and firmly. On account of the square or rectangular shape ofthe pads I33the fitting of replacement pads in the sockets I 36 is arelatively simple matter for a repair or service man. Upwardly directedwall portions I25 formed integrally at the central portion of the frontend of the base are surmounted by a substantially horizontally disposedplatform portion I26. This'platform is thus disposed a material distanceabove'the surface on which the footing portion I24 of the base rests. Avibration absorbing block I21 formed of suitable material such as woodor cork is carried on the platform portion I26 and is surmounted by thehousing 2. Preferably the block I21 fltsinto the socket'35 formed in thebottom of the housing so that the top sides of the block are embraced bydepending portions I28 of the socket. Similarly, the upwardly directedwalls I25 of the base extend above the level of the platform I26 toembrace the bottom sides of the block I21.

In plan form the block I21 is non-circular in shape, preferably beingsquare or. rectangular. The depending portions I28 of the socket areformed to a corresponding shape as are also the upwardly projectingportions of the walls I25 of the base so that when-"the block 'I21 isproperly seated on the platform I26 and in the socket 35 the burnerhousing 2 is correctly aligned with Y respect to the base I.

by a reversal of these 0 erations and is facili tated by the arrangementwhich permits the relatively heavy unit of assembled moving parts to besupported by the bracket or member 5 leaving the operator's hands freeto place and adjust the parts.

Another feature of the construction is that if desired the unit. ofmoving or drive and driven parts may be taken from the burner by withdrawing the three studs or cap screws fi'which secure the supportingmember 5 to the housing 2. This procedure .may be preferred when theidentical unit of movable parts is to be replaced in the burner aftersome minor adjustment, since a fewer number of bolts, studs or screwsare removed than when the cradle I I5 is removed from the bracket 5. Thereassembling of the device when the entire bracket and drive unit havebeen removed is facilitated'by the use of .a locating or guide pin I22secured in the housing and having sliding enaggement in'a hole in thebracket 5 which partially supports and locates the bracket until thestuds 6 are in place. The pin I22 is also used in originally assemblingthe'burner at the place of manufacture. Its location at the A stud I29is secured in the central portion of the socket 35 andextends downwardlythrough an aperture in the center of the block I21 and has a loose fitin a central hole formed In the' platform I26. The parts are drawntogether by a nut I30 which forces a washer I3 I of a material havingthe capacity to deaden vibrations, such as lead, upwardly against thebottom of the platform portion I26.

Adjustment of the burner to different heights is effected by alteringthe height of the supporting block I21, for example, in Fig. 9 isillustrated a block I32 which may be used when elevating the burner.This block if desired may be made of rubber as shown so as to impartincreased merely moving up or down in the space I21 acvibrationabsorbing capacity to the base. The

cording to whether the burner is raised or lowered. Thus a. concealedheight adjustment is afforded which is of material advantage ininstalling the burner since no special equipment other than a supply ofdifferent sized blocks I21 for adjusting the base is required.

Another advantage of .the construction described is that a doublecushioning efiect for the moving parts is provided. The first cushioningis through the medium of the annular rubber rings which support themotor 1 in the cradle II5. Such vibrations as are not dampened at thispoint and are carried to the burner housing 2 are further diminished bythe vibration absorbing block I21 which constitutes the sole support forthe burner housing on the base I. The stud I29 does not operate tosupport the housing 2 since it does not bear down on any part of thebase and its sole contact therewith is through the vibration deadeningwasher I3 I.

Figs. 13 and 14 illustrate a modification in the operation of the airinlet gate 91 when it is desired to retain the latter open at all timesso that a flow of air through the burner is permitted after the blower 9stops. In this modification the enlarged knurled head I is eliminatedfrom one of the pivot screws 99 and the latter provided with ascrewdriver slot I34 for turning the same. The pivot screw is ofincreased length to receive on the portion thereof extending outside ofthe hood 94 a spring I35. One end I36 of the spring bears against thefront wall 31 of the housing 2 to prevent rotational movement of thespring on the pivot screw 99 and the opposite end I31 of the spring isbent underneath the side wall of the hood 94 into engagement with theunder side of the air gate 91 to urge the latter in a clockwise pivotalmovement as viewed in Fig. 13 into engagement with the foot III of theadjusting rod I04. Accordingly, the spring I35 retains the gate 91 openas far as is permitted by the particular adjustment of the rod I04preventing the gate from dropping by gravity to closed position when airis no longer forced through the burner by the blower 9.

In Figs. 15 and 16 is illustrated a modified construction of the burnerwhich is designed for use in connection with a furnace or heater havinga recess or pocket I40 to accommodate the burner. Furnaces of thischaracter are usually constructed of steel or iron and the pocket may beformed of a single casting having integral rear, side, top and bottomwalls I4I, I42, I43, and I44, respectively. The burner is provided witha base I45 similar to the base I previously described and which rests onthe bottom wall I44, the latter inclining upwardly toward the rear wallI4I of the pocket I40. A horizontally disposed track I46 is positionedover the bottom wall I44 of the pocket and supports and guides theburner when the latter is slid into -or out of the pocket. A dependingleg portion I41 of the track I46 extends downwardly across the frontmarginal edge of the bottom wall I 44 and is secured by a stud I43 whichextends through a flange on the bottom wall and into an upwradlydirected flange formed on the margin of base I49 of the furnace. Thebase I45 is formed with longitudinally extending bearing portions I50which have sliding engagement with the top and sides of the track I46 atmarginal edge portions so that the burner is wholly supported by thetrack and guided for straight line movement. Upon withdrawing the burnerfrom the pocket I 40 2. depending apron I52 formed along the rear edgeof the base serves as a support for the burner when the center ofgravity thereof moves ,beyond the end of the track I46. y

In order that the burner may be substantially wholly received within thepocket I40, the length of the combustion air passage I1 is materiallyshortened so that the mouth 58 of the head is to impart increasedresiliency thereto.

relatively close to the inlet end I6 of the passage. Desir bly, theburner may be provided with an integral head and air or blast tube I53which projects through an opening I54 in the rear wall I4I of thepocket. The head I53 is provided with a flange I55 corresponding to theflange II previously described and which is disposed against the frontend wall 31 of the burner housing 2, being secured thereto by studs I56.The head I53 is frustoconical in shape converging toward the mouth 58thereof and effecting a seal with insulating material I51 disposed in aplurality of layers between the rear wall I4I of the pocket I40 andrefractory lining lfifl of the furnace combustion chamber I59.

The fuel pipe 2| is supported in the head I53 by the spider 23 havingsliding engagement with cylindrical portion I60 of the passage formedinternally therein and which corresponds to the cylindrical portion 49previously described. A bracket I62 positioned within the inlet end I6of the air passageway I1 carries the fuel pipe 2I and electrodes 68 and69 in a manner similar to the bracket 22 previously described. Ahorizontally disposed foot portion I63 of the bracket I62 rests on thefloor of the inlet portion I6 of the air passage in the lower part ofthe housing 2 and hasan elongated slot I64 received on the upwardlyextending end of a securing bolt I65. This bolt extends upwardly throughthe platform portion I26 of the base I45 supporting block I21, and isthreadedly secured in the bottom of the housing 2. The upwardlyextending end of the bolt I65 is in the nature of a stud which receivesa tightening nutto lock the bracket I62 in adjusted position. Additionalholding bolts I66 extend upwardly between the platform portion I26 ofthe base and housing 2 through the block I21 being threadedly secured inthe housing to reinforce the connection between the base and housing.The lead washers I3I are employed as previously described to deaden thetransmission of vibrations from the housing to the base.

The electrical connections between the conductors 14 and 15, leadingfrom the transformer, and electrodes 68 and 69, are eiiected by springbrushes I61. formed of suitable material such as bronze or brass andhaving a reverse be'nd I 68 These brushes are secured by screws I69 tothe conductors 14 and 15 and extend upwardly across the axes of theelectrodes 68 and 69.

The adjusting rod I04 for .the air gate 91 has secured on its upper endabove the hood 94 a cylindrical head I10 which has a transversescrewdriver slot I12 formed across its upper end so that adjustment ofthe air gate may be effected without reaching ones hand into the head I10 which is relatively close to the hot walls MI and I43 of the furnacepocket. The spring I08 is made of sufficient strength so that thefriction of the indexing pin I 06 and washers I09 and I I0 is suflicientto prevent inadvertent movement of the adjusting rod I04. A rubbercovered pin I03 secured in the front wall of the hood 94 at the bottominside edge thereof, limits downward pivotal movement of the air gate91.

Desirably the burner as illustrated in Figs. 15. and 16 is secured inplace within the pocket I40 by screws I13 which extend through the baseI45 and are threaded into the bottom wall I44 of the pocket. Thesescrews prevent sliding movement of the base on the track I46 and resistlateral tipping and vibration of the burner. Other parts of the burnerwhich correspond to parts previously described have been indicated bythe same numerals of reference.

The unique design of the burner housing 2 provides a wiring box I'llbetween the outside walls of the housing and the internal partitions 38and 42. A removable plate or plates IBI held in place by a screw orscrews I15 secured in a boss I16 formed on the partition wall .38 closethe opening in the side wall 3| leading into the terminal or wiring boxIll. .Thus but a single electrical conduit III leads to the burner andenters the wiring box I" through a fitting I18 in the removable sidewall plate 3|. The power leads I19 to the transformer extend through acored hole I80 (Figs. 3 and 5) in the rear wall 26 of the housing andthe power leads I82 to the motor I pass through a coredhole I83extending through both the rear wall 36 of the housing and the uprightportion II9 of the bracket 5. Accordingly, the wiring leads for theburner are substantially concealed and protected from injury. During theopening or closing of the aperture 11 of the housing 2 by the pivotingmovement of the transformer casing I3, the primary leads I19 to thetransformer move through the hole I80, there being suillcient slackprovided in the leads I19 within the wiring box I'll to permit thismovement. As shown in Fig. 3, the hole I80 is covered by the transformerbox 13 when the burner is in operation. I

The fuel pressure conduit I9 extends through a slot I84 formed in therear wall 36 of the housing and which is formed radially from theopening I1. Accordingly, when the transformer box I3 is I pivoted toopen position, the conduit I9 may be readily removed longitudinallythrough the passage and out the opening 11 merely by sliding it out ofthe slot I84. Preferably a rubber grommet (not shown) fits around theconduit I9 in the slot I84 to prevent the flow of air-therethrough andwear of the conduit on the walls of the slot.

Oil burners constructed in accordance with the design of the presentinvention exhibit improved operating characteristics. Particularlyadvantageous are the features relating to the flow of air which travelsin a helical path through the combustion air or blast tube and is givenincreased turbulence and agitation in the region of the nozzle 25. Theinlet end of the air passageway through the combustion air tube which isformed in the housing of the burner is of no greater crosssectional areathan the inlet end of the air tube so that air forced tangentially intothe inlet end of the passageway I! from the blower chamber I4 and throatI5 is substantially immediately given a spiral or helical path bythesloping or inclined wall 42.

During operation of the burner, combustion air,

directed tangentially into the inlet end I6 of the air passageway H bythe curved wall 34 of the g throat I5, moves in a curved path whichdevelops into a spiral path as the air travels forwardly through thetube 3. On account of the taper of the passageway H in the portion 48 ofthe air tube the spirally moving column of air is gradually acceleratedso that its velocity is greater as it enters the head 21 than whenleaving the cylindrical portion 41 of the tube.

The increased taper of the conical internal walls of the head 21 betweenthe shoulders 56 and 51 with respect to the taper of the portion 48 ofthe air tube, further accelerates the combustion air in the region ofthe nozzle 25 so that the maximum velocity of the column of spirallymoving air is substantially in the plane of the orifice 26 of thenozzle. Liquid fuel oil forced by the pump through the conduit I9 andpipe 2| is projected under high pressure from the orifice 28 of the male25 in the form of finely divided particles or droplets into the rapidlyrotating stream or vortex of air surrounding and movingpast the nozzle.

The spirally moving air column in the air tube 3 has a greater velocityat the radially outward portions thereof than at the center, and as the'air enters the head 21 the radially outermost or peripheral portions ofthe air stream are deflected by the circumferential shoulder 56 in thepassageway I1 and directed to flow transversely across the helical aircolumn in advance of the nozzle 25 to entrain particles of the sprayedfuel oil. At substantially the region of smallest crosssectional areaand adjacent the extreme outlet efid of the passage H thecircumferential or annular shoulder 51 deflects the outermost part ofthe spirally advanc ng air column to flow transversely across suchcolumn and entrain particles of fuel oil projected from the nozzle 25.In this manner each of the shoulders 56 and 51 serves to createcrosswise currents in the spiral column of accelerated combustion airwhich are beneficial in creating an increased turbulence or agitation ofthe air immediately in advance of the nozzle orifice 26. This increasedturbulence promotes the atomization of the fuel oil into the form of a Imist which increases the operating eiliciency of the burner and resultsin a more uniform and regular combustion flame. Outwardly of the burnermouth 58 the spirally moving air stream expands radially in thecombustion chamber 28. The central part of the air stream is highlyagitated or in a state of great turbulence efiected by the crosscurrents influenced by the shoulders 56 and 51 and the outer portion ofthe air stream continues to move spirally. Fuel oil sprayed from theorifice 26 forms a rich mixture in the highly agitated central portionof the combustion air. Combustion is initiated in this rich mixture andis completed in the outer shell of relatively leaner mixture which isrotating in a spiral fashion. A spark plays across the tip ends of theelectrodes 68 and 69 in the region .of the nozzle orifice 26substantially continuously and insures ignition of the combustiblemixture in the highly agitated central portion of the air stream. Ifdesired, the spark may be discontinued after ignition has been obtainedand the burner is in operation.

The method of burning the liquid fuel carried out by the burner of thepresent invention is particularly successful in overcoming difficultiespreviously encountered in burners which were operated intermittently,such as domestic oil burners. smoky combustion during the heating up ofthe fire box. Another such difficulty is the pulsating or throbbingencountered when a burner is set in operation after a period'ofinactivity. The cause or causes of such pulsations are not thoroughlyunderstood but it has been found that the burner described above,operating in accordance with the method outlined, substantiallyovercomes the objectionable pulsating effects so that entirelysatisfactory intermittent operation can be had. It is believed that theincreased agitation or turbulence and the cross currents immediately inadvance of the nozzle orifice, in combination with the spirallyadvancing aircolumn which is accelerated in its path toward the burnerhead and during its pas One such 'diiilculty is the tendency for sagetherethrough, are instrumental in effecting the improved operation.

In servicing or repairing the burner the movable parts which are movableas a unit, illustrated in Fig. 7, can be quickly replaced so that thereis no substantial interference with the continuous operation of theburner.

The arrangement for controlling the admission of air to the burner isadvantageous in that the amount of air flowing when the blower is inoperation can be regulated while the burner is operating, so thatmaximum operating efliciency of the burner can be quickly established.Additionally, the air inlet gate can be readily converted, from the typewhich remains open a predetermined amount at all times whether theburner is idle or in operation, to the type which is open only when theblo'wer is operating and automatically closes by gravity when the bloweris idle.

Other modes of utilizing the principles of the invention may be resortedto, change being made, as desired, in the particular construction andarrangement of parts shown and described, it being understood thatnumerous modifications and alterations are contemplated and that theembodiments disclosed are given for purposes of explanation andillustration only.

Inventions disclosed but not claimed herein form the subject matter ofmy copending applications Serial Nos. 317,243, 317,244, 317,245 and317,246, all filed February 5, 1940, Serial No. 325,370 filed March 22,1940, and Serial No. 325,761 filed March 25, 1940.

What I claim is:

1. In an oil burner, a housing defining a blower chamber havinggenerally curved-walls, a rotary blower in said chamber and means foractuating the same to rotate a mass of air in the chamber, an air tubeassociated with the housing and cooperatively defining therewith asubstantially straight combustion air passage having an inlet endsubstantially in the plane of rotation of said air mass and an outletspaced from the inlet in a direction parallel to the rotational axis ofthe blower, said inlet end having a cross sectional area materially lessthan the co-planar cross sectional area of the blower chamber, saidhousing including walls defining a passage to receive air tangentiallyfrom the rotating mass thereof in said chamber and to conduct the sametangentially into the inlet end of said combustion air passage to rotatein the latter in the same direction and in the same plane as in theblower chamber about an axis substantially parallel to the blowerrotationalv axis whereby the conducted air is accelerated in the inletend of the combustion air passage by the decrease in area while rotating in the same plane and in the same direction as the air in the blowerhousing, and means for supplying fuel oil in finely divided form tocombustion air discharged from said outlet.

2. In an oil burner, a housing having spaced front and rear walls ofgenerally ovate shape with top, bottom and side walls extending betweenthe edges of the front and rear walls, the top and bottom walls beingcurved, curved partitions extending between the front and rear walls anddividing the interior of the housing into blower and air chambers andproviding a passage between the chambers along one of the side walls,the blower chamber being larger than the air chamber whereby air forcedfrom the blower chamber into the air chamber is accelerated in thelatter, power driven means in the blower chamber for forcing air intothe air chamber, an air delivery tube having one end secured to thefront wall of the housing and communicating with the air chamber throughan opening in said wall, and means adjacent the delivery end of the tubefor discharging atomized oil into air forced through the air tube fromthe housing.

3. In an oil burner, a housing having oppositely disposed front and rearend walls of generally ovate form, with top, bottom and side wallextending between the end walls, the top and bottom walls being curved,partition means extending between the end walls and curved tangentiallyinto the top and bottom walls to provide blower and air chambers withsubstantiallycontinuous curved walls and a passage connecting thechambers and extending along one of the side walls, said air chamberbeing smaller than the blower chamber to effect acceleration of the airin the air chamber, power driven means in-the blower chamber for forcingair through the passage and into the air chamber to rotate in thelatter, an air delivery tube secured at one end to the front end wall ofthe housing and having an elongated passage communicating with the airchamber through an opening in the front wall, said tube passageextending as a continuation of the air chamber and having wallssubstantially flush with the air chamber walls, and meansadjacent thedelivery end of the tube for discharging atomized oil into air forcedthrough the air tube from the housing.

4. In an oil burner, means defining an air passage of elongatedcharacter and circular cross section having spaced cylindrical wallportions of different diameters that substantially parallel thelongitudinal axis of the passage and a tapered wall portion extendingbetween the cylindrical portions, a fuel conduit extendinglongitudinally through the passage, a supporting bracket for theconduit, said bracket having bearing engagement with the largercylindrical wall portion of the passage and being slidable therealong,centering means for supporting the conduit, said centering means beingspaced from the bracket and havin sliding engagement with the smallercylindrical wall portion, one end of the conduit and a source of fuelsupply connected to the other end of the conduit, and means forsecuringthe bracket to said larger cylindrical wall portion of the airpassage in different positions of longitudinal adjustment in thepassage, said bracket and centerin means being adapted for movement as aunit with the conduit whereby the bracket and centering means retain theconduit in fixed relation to the passage axis in different positions oflongitudinal adjustment.

5. In an oil burner, housing and tube means defining a substantiallystraight passage for combustion air generally circular in cross sectionand having an air receiving end and an air discharging end and a blowerchamber communicating with the receiving end of the air passage andarranged to direct air tangentially into said air receiving end of thepassage, a blower mounted in the blower chamber for rotation about anaxis substantially parallel to said straight air passage, the housingand tube means including a wall at the receiving end of the passageinclined to the axis of the straight air passage, facing toward thedischarge and of the passage and disposed in the path of the airdirected tangentially into the passage to direct and guide such airtoward the discharge end, and means for supplying fuel oil to the air atthe discharge end of the straight air passage.

to force the same under pressure through said air outlet, an air tubegenerally circular in cross section and having an air inlet end securedto said housing coaxially with said outlet and having a discharge end, afuel nozzle located axially within said tube at the discharge endthereof. and fuel pump means havingconnection with the nozzle fordelivering oil under high pressure to said nozzle, said air tubeprogressively decreasing in diameter from said inlet end to saiddischarge end toprogressively increase the velocity of combustion airforced therethrough, said housing including air deflecting wall meansadjacent said outlet. said wall means being inclined toward andextending longitudinally with respect to the axis of the air tube fordirecting air from the blower to flow spirally through the tube withgreater velocity adjacent the wall of the tube than at the centerthereof, whereby atomized oil is projected from the nozzle into thecenter of a mass of spirally rotating combustion supporting air.

7. In an oil burner, tube means providing walls defining an elongatedpassage of generally circular cross section for combustion supportingair having ,a relatively long portion tapering from a relatively largediameter inlet end to a relatively small diameter discharge end forprogressively accelerating the velocity of a column of combustionsupporting air moving therethrough, means for introducing combustionsupporting air tangentially into said inlet end and causing such air toflow in a substantially helical path through the passage with a greatervelocity along the walls thereof than in the central portion thereof,said passage including a relatively short portion at the discharge endof the long portion and extending as a continuation of the latter, saidshort sistance to air flowing adjacent such walls, a

circumferentially extending relatively shallow shoulder at one end ofthe short portion of the passage and extending radially inward tointercept the high velocity air moving spirally along the walls of thetube means for deflecting the intercepted air to flow transverselyacross the air column while the flow of air in the central portion ofthe column is substantially unobstructed, a fuel oil nozzle supportedaxially in the short portion of thepassage, and means for supplying oilunder pressure to said nozzle.

8. In an oil burner, an air tube having a longitudinally extendingpassage of generally circular cross section tapered from a relativelylarge diameter inlet end thereof to a relatively small diameterdischarge end thereof for progressively accelerating the velocity ofcombustion air moving through the tube. means for introducing combustionsupporting air into said inlet end of the tube and causing such air toflow spirally through thetube to the discharge end thereof with agreater velocity along the walls of the air tube than at the centralportion thereof, a'burner head secured to the discharge end of the tubeand having a circular passage extending as an axial continuation of thetube passage, said head passage being tapered to effect a furtheracceleration of the combustion air flowing therethrough and ving wallssubstantially unobstructed circumferentially to minimize the resistanceto air flow adjacent such walls, a circumferentially extendingrelatively shallow shoulder substantially at the discharge end of thetube passage and extending radially inward to intercept the highvelocity air moving spirally along the air tube walls for deflecting theintercepted air to flow transversely across the passage in the headwhile the flow of air through the central portion of the tube passage issubstantially unobstructed, a fuel oil nozzle supported axially in thehead passage, and means for supplying oil under pressure I to saidnozzle.

9. In an oil burner, tube means providing walls defining an elongatedpassage of generally circular cross section for combustion supportingair;

-means for introducing air into one end of the passage and causing suchair to flow .in a substantially helical path through the tube means witha greater velocity along the walls thereof than in the central portionthereof, said tube means including a relatively short tapered .portionat the other end thereof to effect acceleration of the air' columnflowing therethrough and having walls substantially unobstructedcircumferentially to minimize the resistance to air flowing adjacentsuch walls, said short tapered portion being provided withcircumferentiallyextending relatively shallow shoulders at the endsthereof and extending radially inward to intercept. the high velocityair'moving spirally along the walls of the tube means for deflecting theintercepted air at both ends of the tapered portion to flow trap verselyacross the moving air column while the flow of air in the centralportion of the column is substantially unobstructed, afuel oil nozzlesupported axially in the air passage, and means for supplying oil underpressure to said nozzle.

10. In an oil burner of the pressure atomizing type, an elongated airtube of generally circular cross section providing a passage forcombustion air and having a relatively long tapered portion and anintegral relatively short cylindrical portion at one end, a burner headsecured on said cylindrical end of the air tube and having a taperedpassage extending as a continuation'of and 'axially aligned with the airtube passage and a discharge opening, a fuel conduit extendinglongitudinally through the tube passage, a fuel nozzle on one end of theconduit and disposed in the head passage, means for supplying fuel oilunder pressure to said conduit, a spider on the conduit and slidin lyengaging the cylindrical portion of' the blast tube whereby the conduitand nozzle can be shifted longitudinally in the tube passage and in thehead passage while retained axially therespider and while the airsurrounds the nozzle immediately prior to release through the headdischarge opening.

11. In an oil burnerof the pressure atomizing type having a blowerhousing and an elongated air tube extending from the housing to providea passagefor combustion supporting air, a chamber in the housingcontinuous with the passage and axially aligned therewith, fuel pumpmeans supported exteriorly of the passage and the chamber, a fuel nozzleand a fuel supply conduit therefor extending longitudinally through thepassage and the chamber, support means for the nozzle and conduit, saidhousing having an opening from said chamber aligned with the passage andof suflicient size to permit axial withdrawal therethrough of thenozzle, conduit and support means as a unit, removable closure means forsaid opening, said support means being inde-- pendent of the closuremeans whereby the latter can be removed for optional inspection or axialwithdrawal of said unit, the housing being provided with a slotextending from said opening to a point beyond the closure means, andsaid conduit normally extending through said slot and connecting to thefuel pumpmeans exteriorly of the chamber and the passage, whereby upondisconnecting the conduit from the fuel pump and withdrawing csaid unitaxially the conduit is moved clear of the slot and is withdrawnsubstantially without bending thereof.

12. In an 'oil burner of the pressure atomizing type having a blowerhousing and an elongated air tube extending from the housing to providea passage for combustion supporting air, a chamber in the housingcontinuous with the passage and axially aligned therewith, fuel pumpmeans supported exteriorly of the passage and the chamber, a fuel nozzleand a fuel supply conduit therefor extending longitudinally through thepassage and the chamber, spaced members supporting the nozzle and theconduit and guiding the same for axial movement in the passage and thechamber, said housing having an opening from said chamber aligned withthe passage and of sufficient size to permit axial withdrawaltherethrough of the said nozzle, conduit and support means as a unit,removable closure means for said opening so disposed and arranged as toprovide with the housing a normally closed end wall for the chamber,said support means being independent of the closure means whereby thelatter can be removed for optional inspection or axial withdrawal ofsaid unit, said end wall being provided with a slot continuous with saidopening, and said conduit normally extending through said slot andconnecting to the fuel pump meansexteriorly of the chamber and thepassage, whereby upon disconnecting the conduit from the fuel pump andwithdrawing said unit axially the conduit is moved clear of the slot andis withdrawn substantially without bending thereof.

13. In an oil burner, an air tube having a passage therethrough forcombustion air and a discharge ,/end, means for forcing air through thetube toward the discharge end thereof, a nozzle at the discharge end ofthe tube for projecting fuel into combustion air, means for supplyingfuel under pressure to the nozzle, and a passage of small crosssectional area relative to the air passage formed in the bottom wall ofthe air tube adjacent the discharge end thereof, said small passageextending longitudinally of the air tube and having one end opening intothe air passage beneath the fuel nozzle and the other end openingadjacent the discharge end of the tube whereby liquid fuel dripping fromthe nozzle is conducted by the small passage out of the air passage andto the discharge end of the tube.

14. In an oil burner of the gun type, air tube means having wallsdefining a passage for combustion air, tube means having an inlet endfor receiving air and a discharge end adapted for connection to the firebox of heating apparatus, means for supplying air to the passage at theinlet end of the tube means, a fuel nozzle supported in the passageadjacent the discharge end, and, a liquid passage separate from the airpassage and having an opening at the discharge end of the tube means,said liquid passage being formed in the lower part of the tube means andextending from a point substantially beneath the nozzle to a point inthe discharge end of the tube means, said passage being inclineddownwardly toward said discharge end whereby liquid fuel dropping fromthe nozzle is received in the liquid passage and conducted thereby intosaid fire box.

15. In an oil burner, a housing of generally ovate form having spacedfront and rear oval wallsand curved walls extending between the edges ofthe oval walls, partition means dividing the interior of the housinginto blower and air chambers each having generally continuous curvedwalls and providing a passage between the chambers for tangentialdelivery of air to the air chamber from the blower chamber, the walls ofsaid chambers including said curved walls of the housing, power drivenmeans in the blower chamber for forcing air into the air chamber throughthe passage, an air tube of substantially circular cross section havingone end secured to the front wall of the housing and communicating withthe air chamber through an opening in such wall and having a dischargeoutlet at the other end, the major portion of the periphery of saidopening being substantially flush with the air chamberwalls and theinside surface of the air tube to effect a non-turbulent flow of airinto the tube from the air chamber, and means for supplying atomizedfuel oil to air released through the discharge outlet of the air tube.

16. In an oil burner of the pressure atomizing type having a blowerhousing formed with an air intake and an air discharge opening, a

blower within said housing to draw combustion supporting air into thehousing and to force the same under pressure through said opening, anelongated air tube of generally circular cross section and having an airinlet end secured to the housing over the opening and coaxially theretoand having an outlet at the other end,

a fuel nozzle and means supporting the same coaxially in the air tubeadjacent the outlet, and fuel pump means having connection with thenozzle for delivering oil thereto under relatively high pressure, saidair tube progressively decreasing in diameter from said inlet end to isaid outlet end to progressively increase the velocity of combustion airforced therethrough,

said housing including curved air deflecting wall means substantiallyflush with said opening and the air tube walls, said wall means beingdisposed to receive air generally tangentially from the blower and beinginclined toward and extending longitudinally with respect to the airtube axis for directing received air to'flow spirally through the tubewith greater velocity adjacent the wall of the tube than at the centerthereof.

17. In an oil bumer, a housing having oppositely disposed front and rearwalls with an a,sio,274

said opening, partition means in the housing and dividing said interiorinto an air chamber in line with the opening and the tube passage and ablower chamber ofiset laterally from said opening, said partition meansalso providing an air passage along one side of the housing connectingthe blower chamber with the air chamber for movement of air from theblower chamber along said housing side and tangentially into the airchamber, a portion of the partition means defining the air chamber beingsubstantially flush with said opening, a blower in the blower chamberand means for actuating the blower to force air from the blower chamberthrough the air passage in the housing and tangentially into the airchamber along one side of the latter whereby air rotates in the airchamber and flows spirally and non-turbulently through said opening intothe air passage in the tube, and means adjacent the other end of the airtube for supplying atomized fuel oil to the spiral stream of air soproduced.

18. In an oil burner, a housing having oppo- I sitely disposed front andrear walls with an opening in the front wall, an air tube secured at oneend to the front wall of the housing over said opening and having alongitudinally extending passage of substantially circular cross sectionaligned with said opening and communicating with the interior of thehousing through said opening, partition means in the housing anddividing said interior into an air chamber in line blower chamber oilsetlaterally from said opening, said partition means also providing an airpassage along one side of the housing connecting the blower chamber withthe air chamber for movement of air from the blower chamber along saidhousing side and tangentially into the air chamber, a portion of thepartition means defining the air chamber being substantially flush withsaid opening and disposed at an acute angle relative to the longitudinalaxis 01' the tube passage, a blower in the blower chamber and means foractuating the blower to force air from the blower chamber through theair passage in the housing and tangentially into the air chamber alongone side of the latter whereby air rotates in the chamber and saidangularly disposed portion of the partition means directs the rotatingair to flow spirally and non-turbulently through said opening into saidair passage in the tube, and means adjacent the other end of the airtube for supplying atomized fuel oil to the spiral stream of air soproduced.

'19. In an oil burner construction, housing and tube means having wallsdefining a substantially straight elongated passage for combustionsupporting air, said passage being of generally circular cross sectionand having an inlet atone end, an outlet at the other end and arelatively large diameter portion between the inlet and the outlet, saidwalls being so formed as to provide a progressive increase in crosssectional area of s the passage between the inlet and said large largediameter portion and the outlet, a nozzle with the opening and the tubepassage and a 1 supported adjacent the outlet, means for supplying fueloil under pressure to the nozzle, and a blower for supplying combustionsupporting air to the passage, said housing and tube means being soconstructed and arranged as to introduce the supplied air tangentiallyinto thepassag'e at said inlet, whereby the introduced air flows atrelatively high velocity along the walls of the passage from said inletto said outlet and the air is first progressively decelerated as the airmoves into the large diameterportion of the passage and is thenprogressively accelerated as the air moves from the larger diameterportion to

